class_docstr: Rule class to handle processing
code: def get_rule(cls, rule_name):
      return Rule._rules.get(rule_name)
  
imports: import ast
  from copy import deepcopy
  import hashlib
  import inspect
  import json
  from streamalert.shared.logger import get_logger
label_desc: Use image node_id 15 for calling the Rule obj's underlying member method code with example usage: obj.get_rule(cls, rule_name) and returns: Rule